U/S to check placenta placement before VBAC?

[Ivy53]

Hi everyone. I am 6 weeks pregnant with my third child. My first was a c-section (which I suspect was unnecessary) and my second was a hospital VBAC. I wanted to get away from regulations like continuous fetal monitoring with the birth of this child so I am going to go to a local birth center - the only birth center within a half hour's drive that takes VBACs. (there is another one about 33 miles away but would take from 40 - 90 minutes to get there depending on traffic, maybe even more)

So I went and took the tour and interviewed one of the midwives and everyone seems nice and the facility seems nice. So I'm trying to pay my deposit and I get a call from the head midwife. She says that in order for them to be allowed to do VBACs they have to follow certain rules. Like having a supportive back-up doc, being near enough to a local hospital, etc. But one of the things she said they had to do was do an ultrasound at around 20 weeks to make sure the placenta wasn't covering my scar.

I have never heard of this before. I did have an ultrasound around 20 weeks with my younger boy, but I don't remember them saying one way or another why the placenta was vis a vis my scar or if it was something they needed to know. I do recall them saying they had to use a nicer u/s machine because they said it was hard to see my son because having a c-section meant I had some scar tissue in my abdomen blocking their view. But can they actually accurately see where my c-section scar is? How often does this happen that the placenta covers the scar? Is it actually dangerous? Does it mean that I have to have a c-section, or just that I'm too "high risk" to have the baby at the birth center?

I'm going to do some research online, but I was wondering if any of you have any experience with this?

[waluso]

I am planning an hbac and my midwife told me I would need an ultrasound to check the placement of the placenta to make sure it isn't over my scar. She said the hospital may not care but she is required to have an ultrasound report. At my 20 week ultrasound my placenta was anterior and very low, so I had to have another ultrasound between 30-32 weeks to make sure it moved. I just had that second ultrasound last week and it was fine. Apparently the placenta should move up unless it was embedded into the scar. Btw, I am also in california so maybe there is some rule on it here. I know friends in other states who didn't have to get an ultrasound for a VBAC.

[Ivy53]

Thanks for your reply. I have heard about placentas moving up (like women discussing a placenta previa that was a problem early on not being a problem by the birth) but now I'm sort of worried about this because I asked if I would get a chance to see if the placenta moved up before the birth if this were to happen and my midwife told me that placentas grow upward but that they don't move. That didn't sound right to me then either.

I have read since last night though that anterior placentas are less likely than the other type, so hopefully this won't be a danger for me. I'm glad yours moved out of the way.

[waluso]

My understanding is that the placenta doesn't move around within the uterus, but as the uterus grows upward, the placenta moves upward with it. It was explained to me that the only way it wouldn't move upward and over my scar is if it had embedded within the scar. When I had my 20 week ultrasound, the dr doing the ultrasound was confident that it would move up and over my scar, and so was my midwife and OB.  And that's exactly what happened. So I don't think your midwife is quite right. One thing to note is my scar is really, really low so that probably helps. But at 20 weeks my placenta was really, really low as well (almost previa). But hopefully your placenta will be posterior and you won't have to worry about it!

[justKate]

I sort of like the reassurance of knowing that the placenta is away from my c-section scar.  My midwives also wanted to know--unfortunately, some other issues arose and I had a couple extra scans, but placenta is posterior along the top of my uterus.  One less thing to worry about, for me.

[AlexisT]

I would also want to know. Keep in mind that a placenta over the scar might also cause problems for a section so it's not a scare tactic. More likely, OBs/MWs who insist on this had a bad experience or know of one.

OP, what it means if the placenta is over the scar is that you might (this is not likely at all after 1 CS but the risks go up with each section you have) have a complication of the placenta known as placenta accreta, where the placenta burrows into the uterine wall. Because of the scar tissue, the placenta will implant more deeply to get enough blood. More extreme forms are called placenta increta and placenta percreta. This is often not diagnosed prenatally, but if they're looking for it, they may find it. In the rare event this happens, it can be very dangerous--even fatal. If you had it, you would need the hospital and a surgeon.

[Mom2SammyJoe]

I was very glad to know I had a posterior placenta with my last VBAC because of concerns regarding acreta.

I have my 20 week scan in 2 weeks. People keep asking if I am going to "find out." Yes, I am going to find out how many babies are in there are where the placenta is. Those are the things that seem important to me. We will not be finding out the gender.

[happyblessedmama]

this isn't a scare tactic, IMO, it's a good thing to know/rule out.

If the placenta covers the scar there's an increased risk of complications, some of which can be exceptionally nasty. I am on my first post-c/s-pregnancy and they did scan me, I do have an anterior placenta but it is not over the scar.